It has long been known that achieving uniform circumferential turbine inlet temperature distribution in gas turbines is highly desirable. Uniform distribution minimizes hot spots and cold spots to maximize efficiency of operation as well as prolongs the life of those parts of the turbine exposed to hot gasses.
To achieve uniform turbine inlet temperature distribution in gas turbines having annular combustors, one has had to provide a large number of fuel injectors to assure that the fuel is uniformly distributed in the combustion air. Fuel injectors are quite expensive with the consequence that the use of a large number of them is not economically satisfactory. Moreover, as the number of fuel injectors increases in a system, with unchanged fuel consumption, the flow area for fuel in each injector becomes smaller. As the fuel flow passages become progressively smaller, the injectors are more prone to clogging due to very small contaminants in the fuel.
This in turn creates the very problem sought to be done away with through the use of a number of fuel injectors. In particular, a fouled fuel injector will result in a non uniform turbine inlet temperature in an annular combustor with the result that hot and cold spots occur.
To avoid this difficulty, the prior art has suggested that by and large axial injection using a plurality of injectors be modified to the extent that such injectors inject the fuel into the annular combustion chamber with some sort of tangential component. The resulting swirl of fuel and combustion supporting gas provides a much more uniform mix of fuel with the air to provide a more uniform burn and thus achieve more circumferential uniformity in the turbine inlet temperature. However, this solution deals only with minimizing the presence of hot and/or cold spots when one or more injectors plug and does not deal with the desirability of eliminating a number of fuel injectors to reduce cost and/or avoiding the use of injectors having very small fuel flow passages which are prone to clogging.
The present invention is directed to overcoming one or more of the above problems.